1) Field of the Invention
This invention relates generally to method of etching patterns in a conductive layer in a semiconductor device using a Poly-p-phenylene sulfide (PPS) bottom Anti-reflective coating (BARC) and more particularly to a method for forming Poly-p-phenylene sulfide (PPS) using Physical Vapor Deposition (PVD) as a bottom anti-reflective coating (BARC) over a polysilicon layer and etching the conductive layer.
2) Description of the Prior Art
A major challenge of semiconductor manufacturing is patterning layers of smaller dimensions. In order to pattern layers using light exposure photoresist processes, often a bottom anti-reflective coating (BARC) is formed over the layer to be patterned. The bottom anti-reflective coating (BARC) layer absorbs excess light that is reflected off the underlying layer thus preventing the reflected light from distorting the photoresist pattern.
Problem with current bottom anti-reflective coating (BARC) layers are (1) that the bottom anti-reflective coatings (BARC) are difficult to remove and (2) that CD (critical dimensions) are difficult to control. Conventional bottom anti-reflective coating (BARC) layer are formed of SiON (silicon oxynitride) and organic materials such as organic polymers. BARC layers composed of SiON or organic material are currently removed using wet cleaning. The problem with this process is that residues are formed and polysilicon CD control is not adequate.
Another problem with current BARC process is the inadequate planarization. Inorganic and organic BARCs are usually formed by CVD and spin-coating. The formed layers have non-uniformity in which thickness of edge is larger than in the center.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering U.S. Pat. No. 5,169,494 (Hashimoto): Fine pattern forming method--shows a method of forming a three layer pattern having a bottom electrically conducting organic polymer, a middle inorganic film and a top e-beam resist layer (electrically conductive).
U.S. Pat. No. 5,302,548(Watanabe), U.S. Pat. No. 5,198,153(Angelopoulos), and U.S. Pat. No. 5,545,588(Yoo) shows other photolithographic processes. The book, An Introduction to Molecular Electronics, Edited by Michael C. Petty, Martin R. Bryce and David Blour, First Edition, Edwird Arnold, London (1995), M. Hara and S. Sasabe, Chapter 11, "Organic Molecular Beam Epitaxy", p244-245, discuss techniques for forming ultra thin films.
There is a need for an improved process of patterning polysilicon and polycide structures that allow easier bottom anti-reflective coating (BARC) photoresist removal and better planarization.